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Chapter 8: Q. 31 (page 478)

The mean age for all Foothill College students for a recent Fall term was 33.2. The population standard deviation has been pretty consistent at 15. Suppose that twenty-five Winter students were randomly selected. The mean age for the sample was 30.4. We are interested in the true mean age for Winter Foothill College students. Let X=the age of a Winter Foothill College student.

Construct a 95%Confidence Interval for the true mean age of Winter Foothill College students.

How much area is in each tail? α2=______?

Short Answer

Expert verified

The area covered by each tail isa2=0.025.

Step by step solution

01

Given Information

The mean age for all Foothill College students for a recent Fall term was 33.2. The population standard deviation has been pretty consistent at 15. The mean age for the sample was 30.4.

02

Calculation

The average of a set of data is called the mean. The 95%confidence interval is a set of numbers that you may be 95%positive includes the population's true mean.

The area covered in by each tail is given by a2.

The area by both tails is α=0.05.

α/2=0.052

=0.025

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The 95% confidence interval is:__________________.
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